From 0c5ade0638e8701e1aafb9dc4ccb0e8e9cdb8f49 Mon Sep 17 00:00:00 2001
From: Alexander Barth <barth.alexander@gmail.com>
Date: Thu, 13 Dec 2018 11:30:48 +0100
Subject: [PATCH] issue #19

---
 src/time.jl       | 23 +++++++++++++++++++++--
 test/test_time.jl | 10 ++++++++++
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/src/time.jl b/src/time.jl
index 4d760f87..b8d6584f 100644
--- a/src/time.jl
+++ b/src/time.jl
@@ -5,12 +5,12 @@ if VERSION >= v"0.7.0-beta.0"
     import Dates: UTInstant, Millisecond
     import Dates: year,  month,  day, hour, minute, second, millisecond
     import Dates: daysinmonth, daysinyear, yearmonthday, yearmonth
-    import Dates: monthday
+    import Dates: monthday, len
 else
     import Base.Dates: UTInstant, Millisecond
     import Base.Dates: year,  month,  day, hour, minute, second, millisecond
     import Base.Dates: daysinmonth, daysinyear, yearmonthday, yearmonth
-    import Base.Dates: monthday
+    import Base.Dates: monthday, len
 end
 
 import Base: +, -, isless, string, show, convert, reinterpret
@@ -715,6 +715,25 @@ Simultaneously return the month and day parts of `dt`.
 """
 monthday(dt::AbstractCFDateTime) = (Dates.month(dt),Dates.day(dt))
 
+
+function Dates.len(first::T, last::T, step::DT) where T <: AbstractCFDateTime where
+    DT <: Union{Dates.Day,Dates.Hour,Dates.Minute,Dates.Second,Dates.Millisecond}
+    return Dates.value(last-first) ÷ Dates.value(Dates.Millisecond(step))
+end
+
+function Dates.len(first::T, last::T, step) where T <: AbstractCFDateTime
+    if Dates.value(step) == 0
+        error("the step should not be zero")
+    end
+    len = 0
+    next = first+step
+    while next <= last
+        next = next+step
+        len = len+1
+    end
+    return len
+end
+
 export daysinmonth, daysinyear, yearmonthday, yearmonth, monthday
 
 export DateTimeStandard, DateTimeJulian, DateTimeProlepticGregorian,
diff --git a/test/test_time.jl b/test/test_time.jl
index c68e3816..5a013d79 100644
--- a/test/test_time.jl
+++ b/test/test_time.jl
@@ -362,6 +362,16 @@ for T in [DateTimeStandard, DateTimeJulian, DateTimeProlepticGregorian,
     @test T(Int16(2000),Int32(1),UInt8(1)) == T(2000,1,1)
 end
 
+# time ranges
+
+@test length(DateTimeNoLeap(2000, 01, 01):Day(1):DateTimeNoLeap(2000, 12, 31)) == 365
+@test length(DateTimeNoLeap(2000, 01, 01):Month(1):DateTimeNoLeap(2000, 12, 31)) == 12
+@test length(DateTimeNoLeap(2000, 01, 01):Year(1):DateTimeNoLeap(2001, 1, 1)) == 2
+
+for T in [DateTimeStandard, DateTimeJulian, DateTimeProlepticGregorian,
+          DateTimeAllLeap, DateTimeNoLeap, DateTime360Day]
+
+end
 
 # if @isdefined DataArrays